I've never been in a situation where I relied on location determination simply based off of mobile networks rather than either GPS or wifi. Matter or fact, on my phone if I don't have the setting checked to use wifi networks (which I don't) and I don't have a GPS signal cause I'm indoors I simply get "Unable to get location data" or whatever the message is. I typically rely solely on GPS as even using wifi networks puts me only in a general area - not exactly where I am or which way I am facing. Though I've turned it on for certain apps that really want your location area, like Yelp, just so I could load what is in the area.
Rev.